Field of the Invention
The present invention relates to a flush toilet apparatus that washes a toilet body by wash water.
Description of the Related Art
Conventionally, a flush toilet apparatus using a tank-type or direct-pressure water supply mechanism is widely used as a mechanism for supplying wash water to a flush toilet apparatus body.
The tank-type water supply mechanism is configured to store water in a tank in advance and supply the water to a toilet body as wash water. In the tank-type water supply mechanism, all of the water supplied as wash water needs to be stored in the tank, and there is a problem that the tank mounted on the flush toilet apparatus is large.
After the completion of washing of the toilet body, the tank needs to be at a full water level for the next washing. However, it takes time to pour water into the large tank to reach the full water level. Therefore, continuous washing (at short intervals) is difficult, and there is a problem that the tank-type water supply mechanism is not suitable for a situation in which the flush toilet apparatus is frequently used.
The direct-pressure water supply mechanism is configured to use water pressure in a water supply pipe (water pipe) arranged in a building to supply wash water to the toilet body from the water supply pipe. In the direct-pressure water supply mechanism, the flow rate of the wash water depends on the water pressure in the water supply pipe. Therefore, there is a problem that the washing performance is reduced when the flush toilet apparatus is installed in an environment with low water pressure (for example, upper floors).
A jet-pump water supply mechanism is newly proposed as a water supply mechanism that can simultaneously solve both of the problem in the tank-type water supply mechanism and the problem in the direct-pressure water supply mechanism (see Japanese Patent Laid-Open No. 2004-156382).
The jet-pump water supply mechanism described in Japanese Patent Laid-Open No. 2004-156382 includes a tank storing water, and a jet pump unit is submerged and arranged inside of the tank. The jet pump unit includes a throat pipe. One end of the throat pipe is connected to a channel toward a bowl portion of the toilet body, and an opening is formed on the other end. When water is injected from an injection nozzle toward the inside of the throat pipe through the opening, a jet pump action is induced, and a large amount of water flows toward the bowl portion inside of the throat pipe. Not only the water injected from the injection nozzle, but also the water stored in the tank is drawn in and flows inside of the throat pipe. Therefore, a large amount of wash water is supplied to the toilet body.
Not all of the water supplied as wash water to the toilet body needs to be stored in the tank in the jet-pump water supply mechanism. Therefore, the tank can be smaller than in the tank-type water supply mechanism, and there is an advantage that the time necessary for the tank to reach the full water level can be reduced. A large amount and a constant flow rate of wash water can be supplied to the toilet body even when the flush toilet apparatus is installed in an environment with relatively low water pressure in the water supply pipe.
In one type of toilet body, the waste is pushed out to a drainage channel by wash water supplied to a bowl portion (hereinafter, also called “wash-down toilet body”). The wash-down toilet body, which is also called a “wash-out toilet body”, forms a large water flow from the bowl portion toward the drain pipe to provide momentum to the waste to thereby move the waste to the drain pipe to discharge the waste. Therefore, in the wash-down toilet body, the water flow needs to be maintained until at least the waste gets over a trap portion and moves to the drain pipe. More specifically, the wash-down toilet body needs to continuously receive the supply of wash water from the water supply mechanism.
As already described, the jet-pump water supply mechanism can supply a large amount of water to the bowl portion of the toilet body at a constant flow rate without being influenced by the change in the water pressure in the water pipe or the change in the water level (potential energy) in the tank. Therefore, when the jet-pump water supply mechanism is mounted on the wash-down toilet body, wash water at a constant flow rate is always supplied to the bowl portion until the waste gets over the trap portion and moves to the drain pipe.
However, the present inventors have conducted intensive studies and found that the flow rate of the minimum wash water necessary to discharge waste in the wash-down toilet body is not always constant in the process of washing, and the minimum wash water changes with time. More specifically, the supply of wash water needs to be continued until the waste gets over the trap portion and moves to the drain pipe in the wash-down toilet body. It has become clear that part of the wash water may be wasted if the jet-pump water supply mechanism always supplies water at a constant flow rate.
In this way, the total amount of wash water supplied to the bowl portion can be reduced to further save water in the flush toilet apparatus including the jet-pump water supply mechanism mounted on the wash-down toilet body.
The present invention has been made in view of the problems, and an object of the present invention is to provide a flush toilet apparatus that can reduce the total amount of wash water supplied to a bowl portion, even though a jet-pump water supply mechanism is mounted on a wash-down toilet body.